yǒuyǎngyùndòng kěyǐ bǎochí jiànkāng.

有氧运动 literally means oxygen-present exercise, which is the Chinese term for aerobic exercise.

It is made up of:

• 有氧 = aerobic / oxygen-based
• 运动 = exercise / sports / physical activity

In this sentence, 有氧运动 works as one noun phrase: aerobic exercise.

Because 有氧运动 is a fixed compound meaning aerobic exercise.

In many Chinese noun compounds, a modifier comes directly before the noun without 的:

• 中文老师 = Chinese teacher
• 高速公路 = highway
• 有氧运动 = aerobic exercise

If you inserted 的 here, it would sound less like a standard term and more like a descriptive phrase. The usual form is simply 有氧运动.

Here 可以 means something like can or is able to, but in a general-result sense:

• 有氧运动可以保持健康。 = Aerobic exercise can help maintain health.

It is not asking for permission here, so it does not mean may.

In Chinese, 可以 often has two common uses:

1. permission: 我可以进去吗？ = May I go in?
2. possibility/ability: 运动可以减压。 = Exercise can reduce stress.

In your sentence, it is the second use.

No, it is not strictly necessary, but it changes the tone slightly.

Compare:

• 有氧运动可以保持健康。
  = Aerobic exercise can maintain health / is good for maintaining health.

• 有氧运动保持健康。
  This sounds incomplete or unnatural if you mean aerobic exercise keeps people healthy.

• 做有氧运动能保持健康。
  = Doing aerobic exercise can keep you healthy.

• 有氧运动有助于保持健康。
  = Aerobic exercise helps maintain health.

So 可以 makes the sentence smoother and clearly expresses a beneficial effect.

Yes, 做有氧运动 is also very natural, and in many contexts it may sound even more explicit.

Compare:

• 有氧运动可以保持健康。
  = Aerobic exercise can maintain health.
  This treats aerobic exercise as a general concept.

• 做有氧运动可以保持健康。
  = Doing aerobic exercise can maintain health.
  This focuses more on the action of doing it.

Both are correct. The version without 做 is more concise and slightly more formal or general.

保持健康 is a verb + object/complement-style phrase meaning maintain health or stay healthy.

• 保持 = to maintain / to keep
• 健康 = health / healthy

A useful thing to know is that 健康 can function as:

• a noun: health
• an adjective/stative word: healthy

So 保持健康 can be understood as either:

• maintain health
• remain healthy

That is why it translates naturally into English in more than one way.

It can be understood either way, and that is very common in Chinese.

In this sentence:

• 保持健康 may be read as maintain health (健康 as a noun)
• or stay healthy (健康 as an adjective-like stative word)

Chinese often allows this kind of flexibility where English would force a clearer distinction.

For a learner, the most important thing is:

• 健康 = health / healthy
• 保持健康 = maintain health / stay healthy

Because Chinese often states general truths without explicitly mentioning a person.

有氧运动可以保持健康。 is a general statement, similar to:

• Exercise is good for health.
• Aerobic exercise can keep you healthy.

The sentence does not need a separate subject like people because 有氧运动 itself is the topic/subject of the sentence.

If you wanted to make the human subject explicit, you could say:

• 做有氧运动可以让你保持健康。
  = Doing aerobic exercise can help you stay healthy.

But the shorter original sentence is perfectly normal.

The basic word order is:

Subject/Topic + modal verb + main verb + object/result

So here:

• 有氧运动 = subject/topic
• 可以 = modal verb
• 保持 = main verb
• 健康 = object/result

Pattern:

• A 可以 B
• 有氧运动 可以 保持健康

This is very similar to English:

• Aerobic exercise can maintain health.

It is written: yǒuyǎngyùndòng

Tone by tone:

• 有 = yǒu (3rd tone)
• 氧 = yǎng (3rd tone)
• 运 = yùn (4th tone)
• 动 = dòng (4th tone)

A learner tip:

• The first two syllables are both 3rd tone, so in natural speech the first one often sounds more like a rising tone due to tone sandhi.
• So 有氧 is often heard approximately like yóuyǎng in connected speech, even though it is still written yǒuyǎng.

Yes. 保持 is often translated as:

• maintain
• keep
• preserve

In this sentence:

• 保持健康 = keep healthy
• maintain health
• stay healthy

All are good natural English translations.

A few more examples:

• 保持安静 = keep quiet
• 保持联系 = keep in touch
• 保持平衡 = maintain balance

Yes, 能 could work, but the nuance is slightly different.

• 可以 often suggests possibility, general usefulness, or permission depending on context.
• 能 often emphasizes ability or capacity.

So:

• 有氧运动可以保持健康。
• 有氧运动能保持健康。

Both are understandable, but 可以 sounds a bit more natural for a general health statement like this. It feels like aerobic exercise can be used to help maintain health.

It is neutral and quite natural. It could appear in:

• health advice
• textbooks
• articles
• everyday speech

It is clear and standard Mandarin.

If you wanted a slightly more formal version, you might see:

• 有氧运动有助于保持健康。
  = Aerobic exercise helps maintain health.

If you wanted a more conversational version, you might say:

• 做有氧运动对健康有好处。
  = Doing aerobic exercise is good for your health.

The original sentence is a very normal standard sentence.